LocostUSA.com

im just about to mount my diff in the rear subframe but pondering if i should mount it on bushings or rigidly attach it to the subframe. those not familliar with the mk2 supra diff, it has 10 mounting points, 2 at the top rear and 8 at the front near the drive shaft flange. the diff weighs in at 60 lbs, i would only use 4 of the 10 mounting holes, the front 2 (shear) and the rear top 2 (tension). i would like to mount it this way for simplicity.

any thoughts for advantages/disadvantages of bolting it directly to the subframe vs suspensding it via rubber or poly bushes.

I think maybe some pictures and a little more background are needed if you want good advice.

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Matt Giles
www.gilesprojectcar.blogspot.com

The mounts on the diff itself need to be extremely stiff. Otherwise, the pinion angles and tripod clearance in the cup will vary. Subframe mounts can be soft and not cause these problems. A large movement on a subframe mount 3 feet away from the diff results in a small movement of the diff by comparison.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

ok, heres what i was thinking. making a panel out of .375 6061-t6 and bolting it (8 plcs) between the diff housing and the rear cover, in addition using the front two lower mounts. note that the upper cross member needs to be relieved to make clearance for the casing, the diff also needs to positioned rear about .250. the 3/8 panel would bolt to the rear bulkhead. still lots of bracing and triangulation to be added to the rear subframe. any thoughts.

Here is one way to do it that will allow pinion angle adjustments later. Tack welding instead of final welding as you build allows easier, less time consuming changes when fitting the parts. Build the frame to fit the parts before final welding. Connect the dots as directly as possible and try to eliminate large offset brackets. A bracket hanging off a frame tube acts like a pipe wrench. Forces from the part being held are amplified by the "wrench" and try to twist the frame tube.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12